Maitake

Metadata

Regulatory Status

European Regulatory Bodies

Maitake has not been assessed by the major European phytotherapy regulatory bodies:

• Commission E (Germany): No monograph exists. Maitake was not part of the European herbal tradition evaluated during the Commission E program.
• ESCOP: No monograph. Outside the scope of European assessment.
• EMA/HMPC: No assessment report or monograph. Grifola frondosa does not appear in the EU Community Herbal Monograph program.

Novel Food (EU)

Maitake fruiting body and extracts have been marketed as food supplements in several EU member states. The whole mushroom has a history of consumption in Asia, but concentrated extracts marketed with health claims may require Novel Food authorization under Regulation (EU) 2015/2283.

Chinese Pharmacopoeia

Maitake (Hui Shu Hua) is listed in the Chinese Pharmacopoeia. Traditional TCM indications include strengthening the spleen, removing dampness, and supporting immune function. It is classified as a medicinal mushroom with documented use for digestive disorders and immune support.

Japanese Regulatory Status

Maitake is not approved as a pharmaceutical product in Japan. It is widely available as a food and dietary supplement. The D-fraction extract has undergone FDA IND (Investigational New Drug) review in the United States for Phase I/II studies, which is notable because this grants regulatory recognition of the research preparation without conferring approval status. Despite extensive Japanese research on D-fraction and MD-fraction, these extracts have not received Japanese pharmaceutical approval, though D-fraction research has been led primarily by Japanese investigators, particularly Dr. Hiroaki Nanba at Kobe Pharmaceutical University.

United States

• Dietary supplement: Widely available under DSHEA
• FDA IND status: The D-fraction extract received FDA IND approval for Phase I/II clinical trials in breast and prostate cancer patients, a significant regulatory milestone for a mushroom-derived product
• No FDA GRAS status for maitake extract specifically

Conditions & Indications

Primary (Moderate Evidence)

Immune Modulation in Cancer Patients

The D-fraction and MD-fraction beta-glucan extracts have demonstrated immunostimulatory effects in cancer patients across multiple studies:

• Kodama et al. (2002) conducted an open-label study in 36 cancer patients (Stage II-IV, various types) receiving maitake MD-fraction alongside standard therapy. NK cell activity was enhanced in 11 of 15 evaluated patients. Tumor regression or significant symptom improvement occurred in 73.3% of breast cancer, 66.7% of lung cancer, and 46.7% of liver cancer patients.
• Deng et al. (2009) published a Phase I/II trial in postmenopausal breast cancer survivors demonstrating that oral maitake extract produced measurable and dose-dependent immunological effects, including enhanced monocyte and T-cell function and modified cytokine production.

Blood Glucose Regulation

Preliminary evidence supports maitake’s role in glycemic modulation:

• Konno et al. (2001) demonstrated that maitake D-fraction enhanced insulin sensitivity and reduced blood glucose in KK-Ay diabetic mice at oral doses equivalent to 1 g/kg/day.
• Kubo et al. (2001) showed that maitake alpha-glucan fraction (the SX-fraction) exhibited hypoglycemic activity in alloxan-induced diabetic mice by enhancing peripheral glucose uptake.

Secondary (Preliminary Evidence)

Lipid Modulation

Animal studies demonstrate that maitake polysaccharides reduce total cholesterol, LDL cholesterol, and triglycerides while maintaining or increasing HDL cholesterol. Kubo and Nanba (1997) showed significant lipid improvements in cholesterol-fed rats receiving maitake powder at 20% of diet. Human data remains limited to small observational reports.

Blood Pressure Regulation

The SX-fraction of maitake has demonstrated antihypertensive effects in spontaneously hypertensive rats (SHR), with proposed mechanisms involving ACE inhibition and improved endothelial function (Talpur et al., 2002). No controlled human trials have been published.

Emerging/Preclinical

• Anti-tumor activity: Maitake polysaccharides, particularly D-fraction, activate macrophages, dendritic cells, and NK cells to generate anti-tumor immune responses. Direct cytotoxicity against cancer cell lines has been demonstrated in vitro, though the primary mechanism is immunomodulatory rather than direct cytotoxic.
• Polycystic ovary syndrome (PCOS): A small open-label study (Chen et al., 2010) suggested maitake extract may induce ovulation in some PCOS patients, possibly through insulin-sensitizing effects. This requires confirmation in controlled trials.

Mechanism of Action

1. D-Fraction Beta-Glucan Immune Activation

The D-fraction is a protein-bound polysaccharide consisting of beta-1,6-glucan backbone with beta-1,3-glucan side chains, with a molecular weight of approximately 1,000 kDa. This structure is critical for its immunological activity:

• Dendritic cell maturation: D-fraction promotes the maturation of immature dendritic cells, enhancing their capacity to present tumor-associated antigens to T-cells. This bridges innate and adaptive immunity against tumors.
• NK cell activation: D-fraction enhances natural killer cell cytotoxicity against tumor cells through upregulation of NK cell activating receptors and increased perforin/granzyme B production (Kodama et al., 2002).
• Macrophage stimulation: D-fraction activates macrophages via Dectin-1 and complement receptor 3 (CR3), triggering NF-kB and MAPK signaling cascades that increase phagocytosis and cytokine production (TNF-alpha, IL-1, IL-12).
• T-cell modulation: D-fraction promotes Th1-type immune responses (IFN-gamma, IL-12 production) while modulating Th2 responses, shifting the immune balance toward anti-tumor immunity.

2. MD-Fraction Purified Beta-Glucan

The MD-fraction is a more highly purified beta-glucan preparation extracted from maitake, with enhanced biological activity compared to crude polysaccharide fractions. MD-fraction has been shown to:

• Inhibit tumor metastasis in animal models by enhancing immune surveillance
• Potentiate the effects of conventional chemotherapy (mitomycin C) in tumor-bearing mice while reducing chemotherapy side effects (Kodama et al., 2002)
• Activate the complement system, leading to opsonization of tumor cells

3. Glycemic Modulation

Multiple compound classes from maitake contribute to blood glucose regulation:

• SX-fraction (alpha-glucan): Enhances insulin sensitivity and peripheral glucose uptake. Proposed mechanism involves activation of insulin receptor substrate (IRS)-1 phosphorylation and downstream PI3K/Akt signaling, increasing GLUT-4 translocation to the cell membrane (Konno et al., 2001).
• Beta-glucans: Slow carbohydrate absorption through viscous gel formation in the gastrointestinal tract.
• Alpha-glucosidase inhibition: Maitake extracts inhibit intestinal alpha-glucosidase, reducing postprandial glucose spikes.

4. Ergosterol and Lipid Metabolism

Ergosterol (provitamin D2) from maitake may contribute to metabolic effects through vitamin D receptor activation. Maitake also contains compounds that inhibit hepatic HMG-CoA reductase (the statin target enzyme), providing a mechanistic basis for observed cholesterol-lowering effects in animal studies.

Clinical Evidence Summary

Phase I/II Clinical Trials

Key Individual Studies

The Deng et al. (2009) Trial — Detailed Analysis

This Phase I/II trial is the most methodologically rigorous clinical study of maitake to date and warrants detailed examination:

• Population: 34 postmenopausal breast cancer patients (free of disease at enrollment), recruited at Memorial Sloan Kettering Cancer Center
• Design: Open-label, dose-escalation with three dose levels of liquid maitake extract
• Key finding: Maitake oral extract produced measurable, statistically significant immunological effects, confirming biological activity. However, the effects were complex — some immune parameters were enhanced while others were suppressed, and the dose-response was not linear.
• Significance: This trial, conducted at a premier cancer center with FDA IND oversight, validated that orally administered maitake has systemic immunological effects in humans, moving beyond purely preclinical evidence.
• Limitations: Open-label design, no placebo control, small sample size, heterogeneous immune responses across individuals.

Evidence Limitations

• No large-scale, randomized, placebo-controlled Phase III trials exist for any indication.
• The Kodama et al. (2002) study, frequently cited in commercial literature, was open-label and non-randomized with no placebo control.
• The D-fraction and MD-fraction are proprietary preparations; generalizability to other maitake products is uncertain.
• Most clinical data comes from Japanese and American research groups associated with the original D-fraction investigators.
• Sample sizes across all trials remain small (n=34-36).
• Heterogeneous cancer types and staging in the Kodama study limit interpretability.

Safety Profile

General Assessment

Maitake has an extensive history as a prized culinary mushroom in Japan, where it has been consumed as food for centuries. The clinical trials conducted to date have reported no serious adverse events attributable to maitake supplementation. The Deng et al. (2009) Phase I/II trial specifically evaluated safety and found no dose-limiting toxicities.

Drug Interactions

Contraindications

• Autoimmune conditions: Immunostimulatory beta-glucans could theoretically exacerbate autoimmune diseases. Use with caution or avoid in systemic lupus erythematosus, rheumatoid arthritis, and similar conditions.
• Pre-surgical: Discontinue at least 2 weeks before elective surgery due to potential antiplatelet activity and hypoglycemic effects that may complicate anesthetic management.

Side Effects

• Common: Generally very well-tolerated. Mild gastrointestinal discomfort (nausea, loose stools, bloating) reported occasionally.
• Uncommon: Allergic reactions in individuals sensitive to mushrooms or molds.
• Rare: Skin rash has been reported anecdotally.

Pregnancy and Lactation

No human reproductive safety data exists. While maitake has been consumed as food in Japan by pregnant women without reported issues, concentrated medicinal extracts (D-fraction, MD-fraction) lack specific safety studies. Avoid concentrated extracts during pregnancy and lactation until safety is established. The whole culinary mushroom consumed as part of a normal diet is likely safe but not specifically studied.

Clinical Dosage

Whole Fruiting Body (Dried)

• Culinary dose: 3-7 g/day of dried maitake (equivalent to approximately 30-70 g fresh weight), consumed as food
• Supplemental dose: 1-3 g/day of dried maitake powder in capsules or tablets

D-Fraction Extract

• Standard dose: 0.5-1 mg/kg body weight per day of standardized D-fraction liquid extract
• Typical adult dose: 35-70 mg/day of D-fraction, taken in divided doses before meals
• The D-fraction has been the primary preparation used in clinical trials and is the most studied dose form

MD-Fraction Extract

• Kodama et al. (2002) protocol: MD-fraction tablets providing 4-6 mg/day alongside whole maitake powder tablets
• This is a more purified preparation than D-fraction, with enhanced beta-glucan content

SX-Fraction (for Glycemic Applications)

• Konno et al. (2013) protocol: SX-fraction capsules providing the equivalent of maitake alpha-glucan standardized to specific glycoprotein content; exact dosing varied
• Limited clinical dosing data; animal-equivalent doses suggest 1-3 mg/kg body weight

Product Quality Considerations

• D-fraction and MD-fraction are proprietary preparations from Maitake Products Inc. (now Mushroom Wisdom); generic maitake supplements may not contain equivalent bioactive profiles.
• Hot-water extraction is necessary to release polysaccharides from chitin matrix; raw maitake powder has lower bioavailability of beta-glucans.
• Products should specify beta-glucan content through validated testing. A minimum threshold of 20% beta-glucans is generally considered indicative of quality.
• Fruiting body extracts are preferred over mycelium-on-grain products, which may contain significant amounts of residual grain starch.

Sources

• Kodama N, Komuta K, Nanba H. Can Maitake MD-fraction aid cancer patients? Altern Med Rev. 2002;7(3):236-239
• Deng G, Lin H, Seidman A, et al. A Phase I/II trial of a polysaccharide extract from Grifola frondosa (Maitake mushroom) in breast cancer patients: immunological effects. J Cancer Res Clin Oncol. 2009;135(9):1215-1221
• Konno S, Tortorelis DG, Fullerton SA, Samadi AA, Hettiarachchi J, Tazaki H. A possible hypoglycaemic effect of maitake mushroom on type 2 diabetic patients. Diabet Med. 2001;18(12):1010
• Konno S, Alexander B, Zade J, Zuniga FI. Possible hypoglycemic effect of SX-fraction in diabetes: a clinical study. J Altern Complement Med. 2013;19(7):614-618
• Kubo K, Nanba H. Anti-diabetic mechanism of maitake (Grifola frondosa). In: Mushroom Biology and Mushroom Products. Penn State, 1997
• Kubo K, Aoki H, Nanba H. Anti-diabetic activity present in the fruit body of Grifola frondosa (Maitake). Biol Pharm Bull. 1994;17(8):1106-1110
• Talpur NA, Echard BW, Fan AY, Jaffari O, Bagchi D, Preuss HG. Antihypertensive and metabolic effects of whole Maitake mushroom powder and its fractions in two rat strains. Mol Cell Biochem. 2002;237(1-2):129-136
• Chen JT, Tominaga K, Sato Y, Anzai H, Matsuoka R. Maitake mushroom (Grifola frondosa) extract induces ovulation in patients with polycystic ovary syndrome: a possible monotherapy and a combination therapy after failure with first-line clomiphene citrate. J Altern Complement Med. 2010;16(12):1295-1299
• Nanba H. Activity of maitake D-fraction to inhibit carcinogenesis and metastasis. Ann N Y Acad Sci. 1995;768:243-245
• Nanba H. Maitake D-fraction: healing and preventive potential for cancer. J Orthomol Med. 1997;12:43-49
• Inoue A, Kodama N, Nanba H. Effect of maitake (Grifola frondosa) D-fraction on the activation of NK cells in cancer patients. J Med Food. 2002;5(4):241-244
• Masuda Y, Inoue M, Miyata A, Mizuno S, Nanba H. Maitake beta-glucan enhances therapeutic effect and reduces myelosuppression and nephrotoxicity of cisplatin in mice. Int Immunopharmacol. 2009;9(5):620-626
• He Y, Zhang L, Wang H. The biological activities of the polysaccharide from Grifola frondosa. Curr Drug Targets. 2018;19(15):1856-1862
• Mayell M. Maitake extracts and their therapeutic potential. Altern Med Rev. 2001;6(1):48-60

Connections

• Compare with Shiitake — both are prized culinary mushrooms in Japan with immunomodulatory polysaccharides, but shiitake’s lentinan has more advanced clinical validation (approved injectable in Japan for gastric cancer)
• Compare with Turkey Tail — PSK/PSP from turkey tail represents the gold standard for mushroom-derived immunomodulators in oncology; maitake D-fraction aims for a similar niche but with less clinical trial volume
• Compare with Reishi — reishi has broader pharmacological activity (triterpenoids + polysaccharides) and a Cochrane review, while maitake’s strength lies in the well-characterized D-fraction/MD-fraction immunology
• Maitake’s dual immune-modulation and metabolic (glycemic, lipid) activity profile makes it unusual among medicinal mushrooms, bridging the immune-modulation and metabolic-support categories
• The D-fraction’s FDA IND status for Phase I/II trials represents a notable regulatory milestone that distinguishes maitake research from many other mushroom investigations that lack formal regulatory oversight
• Synergy with shiitake and reishi is suggested by preclinical data showing enhanced immune responses from combinations of mushroom polysaccharides, though no controlled human trials of combination preparations exist